Combination process for high-octane naphtha production



July 26, 1960 Filed March 29, 195'? I Hi-Ocfane LI. Nap/1M0 7 D. L.MUFFAT ET AL COMBINATION PROCESS FOR HIGH-OCTANE NAPHTHA PRODUCTION 3Sheets-Sheet l Hi -0cfan Reformale To Fuel HYDROFORM/NG 201v:-

Full-Bolling Nap/7M0 Heavy Ends INVENTORS:

Donald L. Muffal William J. Birmingham July 26, 1960 D. L. MUFFAT ETAL2,946,736

COMBINATION PROCESS FOR HIGH-OCTANEI NAPHTHA PRODUCTION Filed March 29,1957 3 Sheets-Sheet 2 m Exuxm QQRQQQQ emmoxmbc 953 J W L INVENTORS:

0000 & 0 0 0 m Q QR E R W QEQEE m fi mm I k M@ Donald L Muffaf WilliamJ. Birmingham IIIiLIIIIMIFP i mum ma July 26, 1960 D. L. MUFFAT EI'ALCOMBINATION PROCESS FOR HIGH-OCTANE NAPHTHA PRODUCTION Filed March 29,1957 INVENTORSI 0 Donald L. Muffaf William J. Birmingham ar ant fireCOMBINATION PROCESS FOR HIGH-OCTANE NAPHTHA PRODUCT-JON Filed Mar. v29,1957, Ser..No. 6,49.,5i58 8 Claims. (Cl. 20865) This invention relatesto a combination process for production of high-octane hydrocarbon fuelsand more particularly to an integratedhydrof-orming-isomerizationseparation process for, preparing high-octanenaphtha base stocks.

Since World War II octane number of motor fuel and aviation gasoline hasrisen .at an accelerated rate along with the increase in compressionratios of piston-type internal combustion engines. 7 To meet thecontinuing demand for higher octane gasoline, refiners have Lde'p'en'dedto a large measure on various catalytic reformingProcesses employingsupported-platinum catalyst. To meet still further increases in octanenumber and .to increase the proportion of premium gradefuels, measuresin addition to hydroforrning are becoming necessary. 'To obtain suchimprovement via the incremental 'hydroforming route would necessitateincreased reforming intensities and charging a higher percentage oftotal available naphtha. Increased reforming intensities involve severeyield penalties. Charging a higher percentage of available naphtharequires use of marginal lighter stocks from which the octaneimprovement is limited and substantiah Isomerization of light naphtha,particularly C s and C s, instead of incremental hydroforrning, is oneparticularly advantageous method of obtaining additional octaneimprovement. It is less costly than incremental hydroforming. Itupgrades the available naphtha which is considered the poorest from ahydroforming standpoint. It provides a high-octane blending stock whichhas a lead susceptibility, i.e., octane response to tetraethyl lead, andoctane blending characteristics which are far superior to those, of.hydroformate. 'Furthermore, isomers of C v and C hydrocarbons have adesirable low Reid Vapor Pressure, and yet a desirable high percentageof low-boiling hydrocarbons, resulting in improved volatilitycharacteristics. 7

It is an object of the present invention to provide an economiccombination of hydrofor'ming .and isomerization which will. producehigh-octane base stocks of superior lead susceptibility, octane blendingcharacter-- It is another object to provide a istics, and volatility.combination hydroforming-isornerization process which will maximizeceiling octane potential. Aiurther object is to separate hydrocarbonnaphtha fractions selectively to provide optimum hydroforming andisomerization charge stocks for octane improvement with maximum yields.A still further object is to integrate hydroforming and isomerization so.as to optimize the yield-octane relationship with a minimum of processequipment and operating costs. These and other objects of our inventionwill become apparent as the detailed description thereof proceeds. 1

For maximum octane potential and optimum octaneyield relationship from acombination of .hydroforming and isomerization we have discovered thatthere are a number of requirements. For example, whenupgradingfull-boiling range naphthas, heavy hydrocarbons i.e.,hy-

drocarbons boiling above about 180 F., should be hydroformed, and normalpentane and hexane in lighter hydrocarbons, i. e., hydrocarbons boilingbelow about 180 F., should be separated and isomerized. Normal pentaneand hexane produced in the hydroforming operafion should be alsoseparated and charged to isomerlization. High octane isomers, e.g.,isopentane, neobexane and diisopropyl, already present in the lighterfraction, should be removed before isomerization t-o maxim'izesubsequent conversion of normal pentane and norhexane. Naphthenes, e.g.,cyclopentane, methylcyclopentane, and cyclohexane, already present inthe lighter fraction, should also be removed from isomerization chargebecause these hydrocarbons already have high octane ratings and asubstantial portion thereof would be cracked to gas duringisomerization. Unconverted normal pentane and norma'lhexane inisomerization product should be separated and recycled so as to obtainsubstantially percent conversion. Furthermore, heavier hydrocarbonsboiling above about F. in product from 'isomerization, which containsubstantial naphthenic material, should be separated and furtherupgraded by hydroforming.

While we have found such selectivity in feed stock ization-separationcombination which achieves this se- I lectivity and other objects 'ofthis invention with sub stantially no more separation equipmentthanlwould 'be associated withrecycle isomerization alone.

ical'ly produce high-octane naphthabase stocks'from by drocarbonslboiling below about 400.5F. by the method which comprises separatingthe hydrocarbons into at least a fraction rich in hydrocarbons boilingaboveabout 180 F. and a fraction rich in hydrocarbon boiling 'belowabout 180 F. charging said fraction rich in hydr'ocarbons boiling aboveabout 180 F. to a hydroform ingzone in the presence of a hydroformingcatalyst and under hydroforming conditions adapted to produce areformate product of higher octane with a ,net productionof hydrogen andadditional hydrocarbons boiling below about 180 F., recyclinga portionof said hydrogen to said hydroforrn'ing zone, charging hydrocarbonsboiling below about 180 F., including the additional hydrocarbonsproduced in the hydroforming zone, to a separation zone wherein at leasta substantial portion of normal pentane and normal hexane in thehydrocarbons boiling below about 180 F. are separated therefrom,charging the separated normal pentane and normal hexane toan'isomeriza'tion zone in the presence of an isomerization catalyst andat least a portion of the remaining hydrogen producedin said.hydroformi'ng zone and under isomerizing conditions adapted to convertat least a substantial portion of saidnormal pent-aneand normal hexanetoisorners thereof, and charging hydrocarbon .efliuent from saidisomerization zone to said separation zone. The high octane productsfrom this embodiment comprise said reformate product and isomers of Cand C (e.g., isopentane, methylpentanes, neohexane, di sopropyl) andother high-octane components (e.g., cyclopentane, methylcyclopentane,cyclohexane, and heavier) from the separation zone.-

in another embodiment of our invention we produce high-octane naphthasby the method which comprises charging substantially olefin-free naphthato a fractionationzone wherein hydrocarbons are separated into at leasta first fraction containing hydrocarbons boiling below about 400 Randabove about 180 F., and a sec- 0nd fraction containinghydrocarbons.boiling below about 180 F. and above'abo'ut 40 F, charging saidpatented .iui 26, read In accord-- ance with one embodiment of ourinvention we econorn first fraction to a hydroforming zone in thepresence of a hydroforming catalyst and under hydroforming condi tionsadapted to produce a reformate product of higher octane with a netproduction of hydrogen and additional hydrocarbons boiling below about180 F., recycling a portion of said hydrogen to said hydroforming zone,charging said additional hydrocarbons boiling below about 180 F.produced in said hydroforrning zone to said fractionation zo'ne,charging said second fraction to a separation Zone wherein at least asubstantial portion of normal pentane and normal hexane in said secondfraction are separated therefrom, charging the separated normal pentaneand normal hexane to an isomerization zone in the presence of anisomerization catalyst and at least a portion of the remaining hydrogenproduced in said hydroforming zone and under iso'merizing conditionsadapted to convert at least a substantial portion of said normal pentaneand normal hexane to isomers thereof, and charging the hydrocarbonproduct from said isomerization Zone to said fractionation zone. Thisembodiment permits separation in a single vessel of hydrocarbons boilingbelow about 40 F. from fresh charge stock and from the products of thehydroforming and isomerization zones. Principal products comprise saidreformate product from the hydroforming zone and C C isomers and highoctane light naphthenes (cyclopentane, and methylcyclopentane andcyclohexane) from the separation zone. These streams may be blended witheach other to form a single high-octane base stock, or, preferably, usedseparately for selective blending.

Advantageous process equipment employed in our sep-' aration zonecomprises fractionating facilities for separating no'rmal pentane andisopentane from remaining hydrocarbons, fractionating facilities forseparating normal pentane'from isopentane, and fractionating facilitiesfor separating normal hexane from said remaining hydrocarbons.Alternatively, :the equipment may comprise fractionating facilities forseparating normal hexane from remaining hydrocarbons, fractionatingfacilities for separating normal pentane and isopentane from saidremaining hydrocarbons, and fractionating facilities for separatingnormal pentane from isopentane. The particular sequence or method is notcritical so long as normal pentane and normal hexane are segregated forisomerization. The zone may, of course, include debutanizationfacilities, although such facilities are usually not required ordesired. It is readily apparent, however, that the combination of thepresent invention requires no more separation equipment than a recycleisomerization unit alone.

Processes for use in our hydroforming zone and isomerization zone maycomprise any of the prior art. The method of the present invention,however, is most advantageously employed with platinum catalysthydroforming processes. In such processes the catalyst usually consistsessentially of alumina, 0.05 to 1 percent by weight of platinum, and 0.1to 2 percent by weight of a halogen, based on dry A1 0 Hydroformingconditio'ns are a temperature in the range of about 800 to 1050 F., apressure in the range of about 100 tov 1000 poundsper square inch gage,a space velocity of about 0.5 to 10 pounds of hydrocarbon charge perhour per pound of catalyst, and a hydrogen rate in the range of about1000 to 10,000 standard cubic feet per barrel of hydrocarbon charge.

A preferred form of platinum catalyst process for use in the combinationof the present invention is Ultraforrning (Petroleum Engineer, vol.XXVI, No. 4, April 1954, at page C-35). Ultraforming operates at lowpressure, i.e., a pressure in the range of about 100 to 400 pounds persquare inch gage, e.g., 300 pounds per square inch gage, a temperaturein the range of about 850 to 1000 F.; a Weight-hourly space velocity ofabout 0.5 to 5, and a hydrogen rate in the range of about 3,000 to 8,000standard cubic feet per barrel.

With respect to the isomerization zone any process capable ofsubstantial conversion of normal pentane and normal hexane tobranched-chain paraffins may be used, including processes employingnoble metal catalyst, e.g., supported-platinum, supported-ruthenium, andthe like. Usually a low temperature process is preferred so as tominimize the amount of recycling required. Low temperature shifts theequilibrium in favor of greater isomerization. Because the presentinvention embodies recycling, however, isomerization processes operatingat relatively high temperatures may also be used.

A particularly advantageous process for use in the isomerization zone inthe isomate Process (World Petroleum, vol. 27, No. 8, July 15, 1956, atpage 68), which features both low temperature and a very activecatalyst. The isomate process utilizes an aluminum halide catalystselected from the group consisting of aluminum chloride, aluminumbromide, an aluminum-chloride-hydrocarbon complex formed by the reactionof anhydrous aluminum chloride with a hydrocarbon in the presence of ahydrogen halide, and an aluminum-bromide-hydrocarbon complex formed bythe reaction of anhydrous aluminum bromide with a hydrocarbon in thepresence of a hydrogen halide. Preferred catalyst is analuminum-chloridehydrocarbon complex. The process operates at atemperature in the range of about to 350 F., preferably about to 300 F.,a pressure in the range of about 500 to 1000 pounds per square inchgage, preferably about 600 to 900 pounds per square inch gage, a spacevelocity in the range of about 0.1 to 10 pounds of hydrocarbon chargeper hour per pound of catalyst, preferably about 0.5 to 5 pounds perhour per pound, and a hydrogen addition rate in the range of about 20 to200 standard cubic feet of hydrogen per barrel of hydrocarbon charge,preferably about 50 to 150 standard cubic feet per barrel.

Hydrocarbons to be up-graded by the method of the present invention arepreferably hydrogen treated befo'rehand in the presence of ahydrogenation catalyst to saturate any olefins and reduce sulfur andnitrogen content. When hydrogen-treating facilities are provided,thermal, colrestill, and/or cat-cracked naphthas as well as virginnaphthas may be treated by the method of the present invention. Hydrogenfor such treatment is preferably obtained from the excess hydrogenproduced in the hydroforming zone. Examples of hydrogenation catalystinclude bauxite, fullers earth, group Vi metal oxides on alumina such aschromia-on-alumina, gro'up V and VI metal oxide mixtures on alumina suchas nickel tungstate, cobalt molybdate or even a platinum-onaluminacatalyst. lumina-supported cobalt-molybdate catalyst is preferred.Conditions for hydrogenation may preferably be a temperature in therange of about 600 to 850 F., a pressure in the range of about 100 to1200 poundsper square inch gage, a space velocity in the range of about1 to 20 liquid volumes of said hydrocarbon streams per volume ofcatalyst. Hydrogen requirements depend on the degree of unsaturation,sulfur and nitrogen contents, and the like. 7

In a preferred embodiment of our invention we upgrade hydrocarbonnaphthas by the method which comprises charging said hydrocarbonnaphthas to a hydrogenation zone in the presence of hydrogen and ahydrogenation catalyst and under hydrogenation conditions adapted tosaturate olefins and to hydrogenate sulfur, sulfur compounds, andnitrogen compounds, charging the hydrocarbon effluent from saidhydrogenation zone to a fractionation zone wherein hydrocarbons areseparated into at least a first fraction containing any hydrocarbonsboiling substantially above about 400 F., a second fraction boilingbelow about 400 F. and above about 180 F., a third fraction boilingbelow about 180 F. and above about 40 F., and a fourth fraction boilingbelow about 40 F., charging said second fraction to a hydroforming zonein the presence of an alumina- Supported platinum catalyst at atemperature in the range of about 850 to 1000 F., a pressure in therange of about 100 to 1000 pounds per square inch gage, a space velocityin the range of about 0.5 to pounds of hydrocarbon charge per hour perpound of catalyst, and a hydrogen rate in the range of about 1000 to10,000 standard cubic feet per barrel of hydrocarbon charge, whereby areformate product of higher-octane is produced with a net production ofhydrogen and additional hydrocarbons boiling below about 180 F.,withdrawing as a product said reformate, recycling a portion of saidhydrogen to said hydroforming zone, directing another portion of saidhydrogen to said hydrogenationzone, charging said additionalhydrocarbons boil'ing below about 180 F. to said fractionation zone,-charging said third fraction to a separation zone wherein at least asubstantial portion of normal pentane and normal hexane in said thirdfraction is separated therefrom, withdrawing as a product from saidseparation zone the remaining hydrocarbons boiling below about 180 F.,charging the separated normal pentane and normal hexane to anisomerization zone-Vin the presence of an aluminum chloride-hydrocarboncomplex catalyst, formedby the reaction of anhydrous aluminum chloridewith a hydrocarbon in the presence of hydrogen chloride, at atemperature in the range of about 100 to spawns from line 13 may also beused. Efiiuent from hydrogen treating zone 12 ischarged via line 14 tofractionation zone 15, along with effluent from isomerization zone 16,

' which is charged to fractionation zone via line 17, and

300 F., a pressure in the range of about 500 to 1000 pounds per squareinch gage, a space. velocity in the range of about 0.1 to 10 pounds ofhydrocarbon charge per hour per pound of catalyst, and a hydrogenaddition rate, from said hydroformingzoneto said isomerization zone, ofabout.20 to 200 standard cubic feet of hydrogen per barrel ofhydrocarbon charge, whereby at least a substantial portion of saidnormal pentane and normal hexane is converted to isomers thereof, andcharging the hydrocarbon effluent from. said isomerization'zone to saidfractionation zone. V,

The invention will be more clearly understood from the followingdetailed description read in conjunction with the accompanying drawingswhich form a part of this specification and in which V Figure 1 is aschematic flow diagram'showing a preferred embodiment which includeshydrogen treating and a common fractionation zone for separating.C Chy-' drocarbons' from fresh charge and from the products of theisomerization zone and the hydroforming zone,

.Figure 2 is a schematic flow diagram of the ultraforming process, whichis the preferred process for use'in the hy droforming zone of Figure 1,and; V Figure 3 is a schematic flow diagram of -.the isomate 50 process,which is the preferred process for use in the: isomerization zone ofFigure 1.

light hydrocarbons boiling below about 180 F. from hydroforming zone 18,which are charged via line 19. While lines 17 and 19 are shown asintersecting line 14, it should be understood that line 17 and 19 may,alternatively, enter fractionation zone 15 separately.

In fractionation zone 15 light hydrocarbons, primarily C -C hydrocarbonsboiling below about 40 F., are removed overhead via line .20 as fuel orfor other purposes, e.g., alkylation, vapor pressure control, and thelike. Heavy hydrocarbons, if any, e.g., hydrocarbon boiling above about400 F., are removed from fractionation zone 15 via line 24. Hydrocarbonsboiling in the range of about 40 to 180 F, i.e., isopentane, normal'pentane, cyclopentane, neohexane, diisopropyl, methyl productspecifications limit end-point of reformate prod-.

net, the width of the fraction, i.e., the end-point, leavingfractionation zone '15 via line 23 maybe tailored accordingly. Thus, thefraction may be, for example, 180 to 360 F., and hydrocarbons boilingabove about, 360

any, would then be removed via line 24. It should "also be understoodthat hydroforming zone .13 may also include extraction facilities and/orfractionation facilities for recycling operations.

The cut-point of about 180 F. in fractionation zone 15 removes, forexample, cyclohexane from reformer charge. This is usually preferredbecause the effective or blended research octane number of cyclohexanemay be higher than that of benzene, to which cyclohexane would beconverted with some shrinkage in hydroforming zone 18. The blendingoctane of any particular hydrocarbon depends in part, ofcourse, on thenature of the base stock into which it is blended. In some blends theblended octaneof cyclohexane may be lower than The feed stock in thisembodiment is typically a Mid- V continent naphtha containing about .03percent by weight of sulfur and having an ASTM end-point in the range ofabout-400-450 F. It consists chiefly of parafiins and naphthenes,naphthenecontent being in the range of about 30-50%. Such a chargestockmay have a F1 octane number of about 10-50. it. may also containcracked materials, e.g.,' thermal, cokestill and/or catcracked naphtha,in which event hydrogen pretreating is necessary to saturate olefius andreduce jsulfur and nitrogen content. a

Referring to Figure 1, such a full-boiling naphtha from source 10 ischarged via line, 11 to hydrogen-treating zone 12. In hydrogen treatingzone 12 olefins are saturated, and sulfur, sulfur compounds,, andnitrogen compounds are hydrogenated in the presence of a hydrothat ofbenzene, just as the unblended octane is lower.

In such cases, or inthe case, of petrochemical manufacture, it may bedesirable to include cyclohexane in charge to hydroforming zone 18. Inthis event fractionation zone 15 is. adjusted so that hydrocarbonsboiling in the range of about 170 to 400 F., rather than 180 to 400genation catalyst, e.g., alumina-supported cobalt r'nolybdate, at atemperature'in the range of about 600-850 F.,

a pressure in the rangeof about -1200 pounds per square-inch gage, avolumetric space velocity in the range of about 1 to 20, and 'inthepresence of hydrogen intro duced from line.13. Stripping facilities (notshown) are preferably employed to remove the hydrogenated sulfur andnitrogen compounds, for which purpose hydrogen F., are chargedtohydroforming zone 18. Likewise, only hydrocarbons boiling below F.would be returned via line'19, and such operation should be consideredwithin the scope of the present invention. In no case should the outpoints be lowered to the point where any substanufacture, e.g;,aromatics production. Light hydrocarbons, i.e., hydrocarbons boilingbelow about R, which were produced in hydroformingzone 18, are removed"via line 19 and charged to fractionation zone 15 via line 14. While allhydrocarbons boiling belowabout 180 are shown as leaving hydroformingzone 18 via line 19, it should be understood that the method'of the pres'moving and separating normal and isopentane. "equivalent fractionatingarrangements are understood to ent invention requires that onlyhydrocarbons boiling in the range of about 40 to 180 F. be removed andcharged to separation zone 22, preferably via fractionation zone 15. Ifhydroforrning zone 18 contains stabilization facilities for removing C Chydrocarbons, a 40 to 180 F. fraction may be charged directly via lines19, 19a, and 21 to separation zone 22, thereby by-passing fractionationzone 15. Likewise, if separation zone 22 contains stabilizationfacilities for removing butane and lighter hydrocarbons, allhydrocarbons boiling below about 180 F. from hydroforming zone 18 may becharged directly via line 19, 19a, and 21 to separation zone 22.

Separation zone 22 comprises facilities for removing normal pentane andnormal hexane from the total charge entering separation zone 22 via line21. This charge contains hydrocarbons boiling in the range of about 40to 180 F. separated from other hydrocarbons in fractionation zone 15 andmay also include stabilized light hydrocarbons from hydroforming zone 18charged directly-via line 19 and 19a and/or stabilized product fromisomerization zone 16 charged directly via lines 17 and 17a. The usualand, in the case of isomerization zone efiiuent, preferred operation,however, is to charge these materials via fractionation zone 15.

In Figure 1 separation zone 22 comprises depentanizer v 26,deisopentanizer 27, and deisohexanizer 28. Isopentane and normal pentaneare separated from the remaining heavier hydrocarbons in depentanizer 26and are charged via overhead line 29 to deisopentanizer 27. Here,isopentane is removed as an overhead product via line 30, and normalpentane is removed as bottoms via line 31 and charged via line 32 toisomerization zone '16. Bottoms from depentanizer 26 are charged vialine 33 to deisohexanizer 28. In deisohexanizer 28 hydrocarbons boilingbelow about 150 F., i.e., cyclopentane, neohexane, diisopropyl andmethylpentanes (Z-methyl pentane and 4-rnethyl pentane) are removedoverhead via line 34. Material boiling in the range of about 150-160"F., i.e., normal hexane, is removed via line 35 and charged toisomerization zone 16 via line 32. For maximum octane, it may sometimesbe desirable to charge methylpentanes, along with the normal hexane, toisomerization, in which event hydrocarbons boiling below about 140 F.are removed overhead via line 34, and hydrocarbons boiling in the rangeof about 140 to 160 F. are charged via lines 35 and 32 to isomerizationzone 16. Material boiling above about 160 F., primarilymethyleyclopentane and cyclohexane is removed via line 36 and may becombined with other high-octane product components in line 37. Ifparticular feed stocks from source contain essentially nomethylcyclopentane and cyclohexane, and if Isomate product and materialboiling below 180 F. from hydroforming zone 18 are charged to separationzone 22 via fractionation zone 15, there may be little incentive toseparate out a bottoms fraction in diisohexanizer 28. In such case, allmaterial boiling above about 150 F. (or, alternatively, 140 F.) fromseparation zone 22 may be charged via line 32 to isomerization zone 16.

While separation zone 22 is shown in this embodiment as hereinabovedescribed, it should be understood that alternative arrangements,requiring substantially no more process equipment, are possible. Thus,feed from line 21 to separation zone 22 could be charged directly todeisohexanizer 28, from which the product fractions would be'the same asdescribed above except that the overhead material leaving via line 34would also include normal pentane and isopentane. This overhead materialwould then be charged to other fractionating facilitiesfor re- Such bewithin the scope of the present invention.

Product from separation zone 22 comprises isopentane from line 30,cyclopentane, neohexane, diisopropyl and 8 methylpentanes from line 34,and methylcyclopentane and cyclohexane from line 36. These streams maybe considered separate products or, optionally, may be combined as ahigh-octane base stock in line 37. Normal pentane which leavesseparation zone 22 via line 31 and normal hexane which leaves via line35 are charged to isomerization zone.16 via line 32. While in thisembodiment normal pentane and normal hexane are shown as being combinedin line 32, it should be understood that each of these streams could becharged separately to isomerization zone 16, should the isomerizationfacilities have separate reactors for pentane and hexane.

' Isomerization zone 16 may comprise any process capable of converting asubstantial portion of normal pentane and normal hexane to isomersthereof. A preferred process for use in isomerization zone 16 is theIsomate Process, which will be described in further detail in Figure 3.Effluent from isomerization zone 16, which contains at least asubstantial portion C and C isomers is charged via lines 17 and 14 tofractionation zone 15, wherein materials boiling below about 40 F. areremoved via line 20 and materials boiling in the range of about 40 to F.are removed via line 21 to be further separated in separation zone 22.Unconverted normal pentane and normal hexane are thus recycled back to Iisomerization zone 16 from separation zone 22 via line 32. Heavy Isomateproduct, i.e., hydrocarbons boiling above about 180 F., which are richin naphthenes, is charged via line 23 to hydroforming zone 18. r

If isomerization zone 16 or separation zone 22 contain stabilizationfacilities for removinghydr'ocarbons boiling below about 40 F., i.e., C--C s efduent from isomerization zone 16 may be charged directly toseparation zone 22 via lines 17 and 17a, rather than indirectly viafractionation zone 15. This should be avoided, however, because it hasthe disadvantage of allowing highboiling hydrocarbons in Isomateproduct, i.e., hydrocarbons boiling above about 180 F. to pass out ofthe system via line 36, rather than via fractionation zone 15, and line23 to hydroforming zone 18,

Hydrogen for use in isomerization. zone 16 is obtained from hydroformingzone 18 via lines 38, 30 and 40. Hydrogen is also recycled tohydroform-ing zone 18 via lines 38 and 41 and may also be utilized vialines 38, 39, and 13 as a reactant and for'stripping purposes inhydrogen treating zone 12. Excess hydrogen, if any, may be withdrawnfrom the system at any convenient point.

While reference has been made in this embodiment to specifichydrocarbons and/or specific boiling ranges and cut points, it should beunderstood that such references are used for descriptive purposes only.It should be understood that perfect fractionation is not an essentialof the present invention and should not be considered as such. Economicconsiderations will influence the design of the fractionation andseparation facilities. Thus, for example, where it is shown in Figure 1that C -C s leave fractionation zone 15 via line 20, that 40180 F.hydrocarbons leave fractionation zone 15 via line 21, that 180-400 F.material leaves fractionation zone 15 via line 23, and that heavy endsleave fractionation zone 15 via line 24, it should .be understood thatthere will be a certain amount of slopover among the respectivefractions. Likewise, such slop-over will occur in the fractionationfacilities of separation zone 22. The degree of separation which iseconomic in any particular installation wouldhave to be analyzed in thelight of the types and relative amounts of the hydrocarbon streams beingtreated, the particular hydroforming and isomerization processesutilized, and the like. It should also be understood that overlap infractionation may be deliberately utilized for particular purposes.Thus, for example, to adjust Reid Vapor Pressure of the base stockleaving separation zone 22 via line 37, some C s could be slopped-overin fractionation zone 15 so that they leave fractionation zone 15 vialine 21 rather than line 20, and ultimately pass via depentanizer 26,line 29, diisopentanizer 27, and line 30 to line 37. Likewise, methylpentanes can be slopped over in deisohexanizer 28 so that at least someare removed with normal hexane via line 35 for charging to isomerizationzone 16. Also, cyclohexane can be slopped over in fractionation zone 15so as to be included in material leaving via line 23 to hydroformingzone 18.

Figure 2 shows a schematic flow diagram of the Ultraforming Process,which is the preferred hydroforming process for hydroforming zone 18.Ultraforming uses an alumina-supported platinum catalyst, in which theplatinum content is in the range of about 0.05 to l per.- cent byweight. The catalyst is loaded in a series of fixed.- bed reactors,usually 3 to 6 in number. A spare or swing reactor is usually providedalong with suitable manifolding lines and valves so that when catalystin any of the onstream reactors becomes deactivated, the swing reactormay be temporarily substituted for it. The deactivated catalyst is thenregenerated by special techniques which fully restore activity. Typicalultraforming conditions are temperature in the range of about 850 to1000 F., pressure in the range of about 100 to 400 pounds per squareinch gage, hourly-weight space velocity in the range of about 0.5 to 5,and hydrogen recycle rate in the range of about 3000 to 8000 standardcubic feet per barrel of naphtha charge stock.

In Figure 2 catalyst in swing reactor 42 is being regenerated, whilenaphtha is being processed in on-stream reactors '43, 44, and 45.Naphtha feed boiling above about 180 F., from line 23 and hydrogen-"richrecycle gas from line 41 are'passe d through furnace 42a Where they areheated to reaction temperature, e.g., 920? F. Naphtha vapors and recyclegas are then mixedin line 46 and passed via lines 47 and '48 to reactor43, thence via line 49, reheat furnace 50, and lines 51, 52 and 53 to Ireactor 44, and finally via line 54, reheat furnace 55, and lines 56,57, and 8 to tail reactor 45. .Reheat furnaces 50 and 55, which, alongWith furnace 42a, may be sections of a single furnace, are requiredbecause of the overall endothermic nature of the ultraforming reactions.

Efliuent from reactor 45 passes via lines 59 and 60 to separator 61,from which is flashed a hydrogen-rich gas via line 38. A portion of thishydrogen-rich gas is recycled via line 41 to furnace 42a. Anotherportion of hydrogen-rich gas passes via line 39 to isomerization zone 16and hydrogen-treating zone 12, as shown in Figure l. Hydrocarbons fromseparator 61 are passed through a second separator 62, from whichproductreformate boiling above about 180 F. is removed via line 25, andhydrocarbons boiling below about 180 F. are removed overhead via line 19and charged to fractionation zone 15 via line 14, as shown in Figure 1.Under certain circums tances it may be desirable to remove light ends,i.e., material boiling below about 180 F., at an intermediate point onthe hydroforming chain, e.g., after the first reactor. This wouldprevent any further cracking of these light ends in subsequent reactors.

When activity of catalyst in a particular reactor declines, that reactoris temporarily isolated from the naphtha processing system, and itsplace is taken by the swing reactor, said substitution of reactors beingmade possible by valved manifolds '63, 64, 65 and 66. Deactivatedcatalyst is'reactivated using 'air from source 67, and inert gas fromsource 68 (usually an inert 'gas generator), which are heated in furnace69 and passed via the appropriate manifolding to the reactor "containingdeactivated catalyst. Reactivation usually comprises a carbon burn-offand/or additional oxygen treats under controlled conditions, i.e., anoxygen partial pressure above about 0.4 atmosphere and a temperatureabove about 950 F. Excess flue gas is removed from the regenerationsystem via line 70. After regeneration, the reactor with regeneratedcatalyst is again placed back on-stream and swing reactor 42 is held inreadiness until catalyst in another reactor.

needs regeneration.

Process.

Figure 3 shows a schematic flow diagram of the Isomat The reactionisconveniently carried out in a simple, cement-lined drum, which ismounted vertically and contains a pool of the liquid catalyst. Thecatalyst is preferably a highly-selective liquid complex of alumi numchloride and hydrocarbon. Hydrogen is also introduced to suppresscracking and catalyst contamination. The naphtha rises through thecatalyst as an insoluble phase and its composition in the efiiuent isclose to equilibrium. High catalyst activity is maintained byperiodically injecting a slurry of fresh aluminum chloride in naphtha.Reaction conditions are typically a temperature in the range of about150-300 F., a pressure of 600 to 900 pounds per square inch gage, and ahydrogen addition rate of about 50 to 150 standard cubic feet perbarrel.

Referring to Figure 3, feed naphtha, i.e., normal pentane and normalhexane (and, optionally, methyl pentanes), enters via line 32 to dryer72, and thence via line 73 to HCl absorber '74, where it picks uphydrogen chloride, said hydrogen chloride entering from line 75. Gas(excess hydrogen) to fuel or for other purposes leaves HCl absorber 74via line 76. Feed stock containing absorbed HCl leaves absorber 74 vialine 7'7 and is charged via pump 78, exchanger 79, and line to reactor71. About 50-150 standard cubic feet of hydrogen per barrel of feed fromline 40 is mixed with feed in line80 prior to entering reactor 71. Aslurry of fresh aluminum chloride in naphtha from source 81 entersreactor 71 via pump 82 and line 83. Spent catalyst leaves reactor 71 vialine 84.

Product effluent from reactor 71 leaves'via' line 85 and cooler 86 andis flashed into a settler 87 for separation of entrained catalyst, saidentrained catalyst leaving by valved line 88. The liquid product leavessettler 87 via line 89 and enters HCl stripper 90 for rem-oval of H01.Gases from settler 37 and stripper 90 leav via lines 91 and 92respectively and are recycled via line 75 to the HCl adsorber, alongwith a small amount of makeup hydrogenchloride from source 93. Liquidproduct leaves HCl stripper 90 via line 94 and is joined in line 95 withcaustic introduced from source 9-6 for washing in caustic wash vessel97. Residue is removed from caustic vessel 97 via line 98 and liquidproduct is removed via line 99 for further Washing in water wash vessel100, water for which is introduced from source 101. Residue from waterwash vessel 100 is removed via line 102, and isomerization zone productis removed via line 17 andreturned to fractionation zone 15 via line 12- as shownin Figure 1. 7

If stabilization facilities are available for removal of .C C4hydrocarbons in isomerization zone 16 eiliuent from isomerization zone16 may pass directly via line 17, 17a and 21 to separation zone 22. Evenif such stabilization facilities are available, however, the preferredoperation is to charge isomerization zone effluent via lines 17 and 14to fractionation zone 15 so that higherthenic heavy hydrocarbons wouldbe removed via line 36 without further upgrading.

As can be seen from the hereinabove specific embodiment, use of aunitized and integrated fractionation and separation zone, combined withhydrogen treating, hydroforming, and isomerization, has a number ofadvantages. For example, hydrogen from hydroforming zone 18 is used inisomerization zone 16 and hydrogen treating zone 12. The samefractionation zone 15 stabilizes and fractionates charge naphtha, lighthydrocarbons from hydroforming zone 18, and efiluent from isomerizationzone 16. Use of such integrated fractionation facilities not onlyminimizes equipment and operating costs but also, and more importantly,eifectively segregates in one operation desired hydroforming charge fromincoming fresh naphtha and from isomerization zone efiluent. Separationzone 22 segregates desirable isomerization zone feed, 'i.e., normalpentane and normal hexane, from fresh light hydrocarbons, hydroformingzone product, and isomerization zone product. same time, the separationzone' eliminates from each of these streams particular hydrocarbonfractions, e.g., cyclopentane, methylcyclopentane, and cyclohexane,which are not considered desirable isomerization zone charge stock.

In brief, the method of the present invention optimizes combinedhydroforming-isomerization operations with the attendant advantages ofmaximum octane potential, highest yield-octane relationship, and theflexibility of providing several high-octane blending stocks withsuperior octane and volatility blending characteristics at a minimum inoperating and investment costs. For example, application of combinedhydroforming-isomerization to a typical refinery situation, as asubstitute for incremental hydroforming, results in both a higher octanemotor fuel pool and lower costs per incremental octane.

While we have described our invention with reference to certain specificembodiments thereof, it is to be understood that such embodiments areillustrative only, and not by way of limitation.

Having thus described our invention, we claim:

1. A combination process for producing high octane gasoline blendingstocks from lower octane naphtha, which process comprises charging saidnaphtha to a fractionation zone, separating said naphtha in said zoneinto at least a first naphtha fraction rich in hydrocarbons boilingbelow about 170-180 F. and a second naphtha fraction rich inhydrocarbons boiling above about 170180 F., hydroforming said secondnaphtha fraction in a hydroforming zone in the presence of platinumalumina hydroforming catalyst, whereby there is produced a net amount ofhydrogen and a hydroformate having a higher octane than said secondnaphtha fraction, recycling a first portion of said hydrogen to saidhydroforming zone, separating said hydroformate into a firsthydroformate fraction rich in hydrocarbons boil ing below about 1701 80'F. and a second hydroformate fraction rich in hydrocarbons boiling aboveabout 170- 180 F. having a higher octane than said second naphthafraction and suitable for use as a gasoline blending stock, chargingsaid first naphtha fraction and said first hydroformate fraction to aseparation zone, separating from the charge to said separation Zone atleast a substantial portion of the normal pentane and normal hexane inthe charge to said separation zone, withdrawing from said separationzone as a gasoline blending stock the remaining hydrocarbons from thecharge to said separation zone, charging said normal pentane and normalhexane and a second portion of said hydrogen to an isomerization zonemaintained under isomerizing conditions adapted to convert at least asubstantial proportion of said normal pentane and normal hexane tohigher octane isomers thereof, and charging the hydrocarbon efiluentfrom said isomerization zone to said separation zone.

2. The improved combination process of claim 1 wherein at least aportion of the hydrocarbon efiiuent from said isomerization zone ischarged to said fractionation zone.

3. The improved combination process of claim 1 At the to a hydrogenationzone.

5. In a combination process for producing high octane gasoline blendingstocks from lower octane naphtha, which process comprises charging saidnaphtha to a fractionation zone, separating said naphtha in said zoneinto at least a first naphtha fraction rich in hydrocarbons boilingbelow about 170-180 F. and a second naphtha fraction rich inhydrocarbons boiling above about 170180 F., hydroforming said secondnaphtha fraction in a hydroforming zone in the presence of aplatinum-alumina hydroforming catalyst, whereby there is produced a netamount of hydrogen and a hydroformate having a higher octane than saidsecond naphtha fraction, recycling a first portion of said hydrogen tosaid hydroforming zone, charging said first naphtha fraction to aseparation zone, separating from the charge to said separation zone atleast a substantial proportion of the normal pentane and normal hexanein the charge to said separation zone, withdrawing from said separationzone as a gasoline blending stock the remaining hydrocarbons in thecharge to said separation zone, charging said normal pentane and normalhexane and a secend portion of said hydrogen to an isomerization zonemaintained under isomerizing conditions adapted to convert at least asubstantial proportion of said normal pentane and normal hexane tohigher octane isomers thereof, and withdrawing a hydrocarbon efiluentfrom said isomerization zone suitable for use as a gasoline blendingstock, the improved combination which comprises separating saidhydroformate into a first hydroformate fraction rich in hydrocarbonsboiling below about 170-180" F. and a second hydroformate fraction richin hydrocarbons boiling above about 170-180 F. suit-able for use as agasoline blending stock, charging said first hydroformate fraction tosaid separation zone, and charging the hydrocarbon eflluent from saidisomerization zone to said separation zone.

6. The improved combination process of claim 5 wherein at least aportion of the hydrocarbon effluent from said isomerization zone ischarged to said fractionation zone.

7. The improved combination process of claim 5 wherein at least aportion of the hydrocarbon eflluent from said isomerization zone ischarged to said fractionation'zone and at least a portion of said firsthydroformate fraction is charged to said fractionation zone.

8. The improved combination process of claim 5 wherein said naphtha,prior to being charged to said fractionation zone, and a portion of saidhydrogen is charged to a hydrogenation zone.

References Cited in the file of this patent UNITED STATES PATENTS2,372,711 Cornforth Apr. 3, 1945 2,443,607 Evering June 22, 19482,678,263 Glazier May 11, 1954 2,758,064 Haensel Aug. 7, 1956 2,777,805Lefrancois et a1. Jan. 15, 1957

1. A COMBINATION PROCESS FOR PRODUCING HIGH OCTANE GASOLINE BLENDINGSTOCKS FROM LOWER OCTANE NAPHTHA, WHICH PROCESS COMPRISES CHARGING SAIDNAPHTHA TO A FRACTIONATION ZONESEPARATING SAID NAPHTHA IN SAID ZONE INTOAT LEAST A FIRST NAPHTHA FRACTION RICH IN HYDROCARBONS BOILING BELOWABOUT 170-180*F. AND A SECOND NAPHTHA FRACTION RICH IN HYDROCARBONSBOILING ABOVE ABOUT 170-180*F., HYDROFORMING SAID SECOND NAPHTHAFRACTION IN A HYDROFORMING ZONE IN THE PRESENCE OF PLATIMUM-ALUMINAHYDROFORMING CATALYST, WHEREBY THERE IS PRODUCED A NET AMOUNT OFHYDROGEN AND A HYDROFORMATE HAVING A HIGHER OCTANE THAN SAID SECONDNAPHTHA FRACTION, RECYCLING A FIRST PORTION OF SAID HYDROGEN TO SAIDHYDROFORMING ZONE, SEPARATING SAID HYDROFORMATE INTO A FIRSTHYDROFORMATE FRACTION RICH IN HYDROCARBONS BOILING BELOW ABOUT170-180*F. AND A SECOND HYDROFORMATE FRACTION RICH IN HYDROCARBONSBOILING ABOVE ABOUT 170180*F. HAVING A HIGHER OCTANE THAN SAID SECONDNAPHTHA FRACTION AND SUITABLE FOR USE AS A GASOLINE BLENDING STOCK,CHARGING SAID FIRST NAPHTHA FRACTION AND SAID FIRST HYDROFORMATEFRACTION TO A SEPARATION ZONE, SEPARATING FROM THE CHARGE TO SAIDSEPARATION ZONE AT LEAST A SUBSTANTIAL PORTION OF THE NORMAL PENTANE ANDNORMAL HEX ANE IN THE CHARGE TO SAID SEPARATION ZONE, WITHDRAWING FROMSAID SEPARATION ZONE AS A GASOLINE BLENDING STOCK THE REMAININGHYDROCARBONS FROM THE CHARGE TO SAID SEPARATION ZONE, CHARGING SAIDNORMAL PENTANE AND NORMAL HEXANE AND A SECOND PORTION OF SAID HYDROGENTO AN ISOMERIZATION ZONE MAINTAINED UNDER ISOMERIZING COMDITIONS ADAPTEDTO CONVERT AT LEAST A SUBSTANTIAL PROPORTION OF SAID NORMAL PENTANE ANDNORMAL HEXANE TO HIGER OCTANE ISOMERS THEREOF, AND CHARGING THEHYDROCARBON EFFLUENT FROM SAID ISOMERIZATION ZONE TO SAID SEPARATIONZONE.